I wonder what sort of cretin ever thought that the realities would ever allow this to work?

        DV82XL said:

The bold passage is why you can’t be taught. Nothing, absolutely nothing will give more energy out than goes in.

Did i say anything against this obvious fact ?

Saying as i did “but it can even get you more energy that you have worked to put in….”
is not at all the same than saying that there will be more energy out than that goes in.

Let me try another way to explain to you :
the natural temperature increase from winter to summer will be enough to heat your scuba diving bottle sleeping in the garage, and heating compressed air inside either.

So in summer, the temperature of your compressed air will be higher than 5°C, and so will be its pressure, exceeding in summer the winter 5°C 200 bars.

You can even take the bottle and, while sleeping and sunbathing, let it laying under direct sun : this is not hard work for you, and i can tell you that compressed air will have more energy to give after a while.

So you may agree :
- that energy in this bottle will by larger in summer than in winter,
- that YOU don’t have to work in order that outer thermal energy come inside the bottle when outer temperature increase,
- and that pressure increase with temperature inside the closed bottle, as described by this famous Ideal Gaz Law you seems to love so much, that you don’t even recognise its application on such a simple situation.

Why do you love so much insulting people and give them negative adjectives ?

Did you notice how often such definitive assertion is applying so well to the individual saying it ?

It will be a great honour for me to answer any of your questions on my previous posts.

Or do you consider that all other facts i did mention are clear enough and right ?

        brnd said:

Sure, it is always easier to attack people than hard facts.

Not only compressed air storage is lossless, but it can even get you more energy that you have worked to put in….

The bold passage is why you can’t be taught. Nothing, absolutely nothing will give more energy out than goes in. The fact that you insolently assert this demonstrates just how little you understand the subject at hand.

Nor is my assessment compressed air car radical in any sense of the word. The things don’t work as well as their supporters think they will because the laws of physics. The concepts at work here are the Idea Gas Law and the three Laws of Thermodynamics. Please at the very least look them up on Wikipedia before continuing. Then if you want to try and pose some intelligent questions for clarifying some of the ways they apply to air cars, I might answer. At this point the obvious depth of your ignorance makes any further exchange with you a waste of my time.

Unless you demonstrate that you have at least tried to understand these things on your own, I will not answer you again.

        DV82XL said:

brnd – You don’t know what you are talking about, it is that simple.

Sure, it is always easier to attack people than hard facts.

Please don’t dilute and mix things in foggy words. Just quote my sentences one by one and tell me what is wrong, i really need to learn from you.

Are you explaining me that you cannot find a way to compute the efficiency of a storage, nor the efficiency of a compressed air engine, nor efficiency of a car ?

If you can, you should teach me by showing me some formula…

I need more explanations on your sentence…. Any explanation about “cold creation” would be nice, for instance.

I will try to explain you :

- take a scuba diving bottle, full at 200 bar, at 5°C which is current temperature in my garage, and store it in your garage.

- Come back 1 month later : if temperature is still 5°C, what will be pressure in this bottle ?
If it is less than 200 bar, take your bottle to support…

- And you know what, if spring happens as usual, temperature will be more than 5°C, and you should see that pressure will be over 200 bar.

Not only compressed air storage is lossless, but it can even get you more energy that you have worked to put in…

And you know what ? Just try to put a full battery on your garage, and come back 6 months later to check how much electrical energy you keep inside…

Yes in this case you would better use a COP (COeeficient of Performance) as there is heat transfer involved, like for heat pump.

Do you mean that power-to-weight ratio is the same concept that energy efficiency ?

Do you mean that temperature and pressure of a gaz have no link with energy content of said gaz ?

I never thought about applying a heat pump to any argument, but i will try to understand that new field of thermodynamic : you seems very efficient at heating arguments.

For me, the 3 stages of :
1- compression ;
2- storage ;
3- decompression.

are quite clear and independant.

I am sure that any decent student in physics can define what inputs and outputs for these stages are, and then will be able to define some meaningful efficiency concept for each of these stages.

Do you mean than moving heat has nothing to do with taking energy from one place and storing this energy to another place ?

Your teaching is so clear and impressive, thank you so much for this beautiful thermodynamic lesson of your own.

I am sure that your very radical assesment on compressed air car is completely explained by the extraordinary thermodynamic knowledge you show us.

Decompression of compressed air, and its storage is not something that can be described as ‘efficient’ to begin with, that parameter does not apply in these instances. Cold is never created as much as heat must be supplied from outside the system, as waste heat must be sunk when compressing it, that in and of itself are counted as thermodynamic losses. Storage, in this the case of compressed air may be loss less, (although in my experience this is never so) but the term ‘efficient’ does not apply unless you are comparing it with some other medium on a power-to-weight ratio or something similar.

Heat pumps move heat, that is their function, that makes them perforce poor at storing energy in the compressed gas they use as a carrier. Not only are heat pumps not applicable to your argument, to they are, they undermine it.

To recap: Efficiency is a measurement that must compare an output to an input, one cannot talk meaningfully about the efficiency of the various stages in this type of system independently. Second moving heat and storing energy are diametrically opposed functions of this type of system – the better it is at one, the worse it must be at the other.

Spend some time to study the Idea Gas Law and the three Laws of thermodynamics. You obviously have no idea what you are talking about, and that too is a clear statement of fact.

        DV82XL said:

Thinking you can ignore the laws of thermodynamics because you find them inconvenient is one of the signs of a crank.
When you demonstrate some grasp of physics, we can continue this conversation.

Are you always insulting people when physics evidences are against your ideas ?

I gave you many facts and figures about decompression stage, storage stage and compression stage.

You agree that decompression stage is efficient and create cold temperature.

You may agree that storage of compressed air is 100% efficient, with no loss at all.

You don’t seem to agree that compression stage is efficient enough, at a minimum of 60% efficiency.

Compression is the basis of all “heat pumps”, and they have the highest Coefficient of Performance we know in industry.

What can i say more ?

What is wrong in what i said ?

I wish you to be able to cope with your emotions…

        brnd said:

Thinking to know everything and all possibilities is natural way to later pain.

Thinking you can ignore the laws of thermodynamics because you find them inconvenient is one of the signs of a crank.

When you demonstrate some grasp of physics, we can continue this conversation.

So we can agree that the decompression stage is very efficient and powerful.

Running cooler is a great natural advantage, both for mechanical behaviour of materials, and for performance : it means that by using low temperature heat, coming from environnement, from solar concentration or from very efficient continuous combustion (95+ efficiency), compressed air engine can absorb thermal power to give more mechanical power.

You have in fact more a natural heat pump than a typical ICE, where excess heat is lost.

Do you mean that the compression stage is not efficient ?

Because storage stage for compressed air is the most efficient storage of mechanical energy i know, as there is NO LOSS at all. You can keep compressed air for years in a tank, without losing any energy. And tank can be very simple, like a hole in the ground and some concrete to make very solid tank.

It is well known to be the most expensive form of energy in any industrial shop. The truth of this can be found via any search in Google.

Current mechanical air compressor with water cooling is having 60% efficiency for 1 bar to 350 bars. It means that 40% of energy used is transformed in heat. This is quite acceptable, specially if you need this heat in the building.

But mechanical compression can be more efficient when it is run slowly. If a car needs a full load daily, then 300litres of air at 300bar, thus 90m3 of air to compress in 24h, that is less than 4m3 per hour. Efficiency can be lot higher at low flow.

If compressors for industrial use are not efficient, may be the reason is that they don’t care, because their power is not expensive enough ? They will have to think and change now…

Let’s take another use of compressors : all Air Conditionning and Heat Pump have a COP of minimum 3, and their only mechanical part is … a gaz compressor. Very inefficient, isn’it ?

        DV82XL said:

Any idea that has compressed air used as motive power in any transportation medium will by necessity be forced to assume this low efficiency; there is no way to avoid it.

Or is there only no way you know ?

Think about heat pumps…

        DV82XL said:

Those that back this as a solution to transport only demonstrate a deep ignorance of basic physics, and fundamental engineering principles.

And will they also burn in hell for eternity ?

Thinking to know everything and all possibilies is natural way to later pain.

But the one thing compressed air is not is efficient. It is well known to be the most expensive form of energy in any industrial shop. The truth of this can be found via any search in Google. Any idea that has compressed air used as motive power in any transportation medium will by necessity be forced to assume this low efficiency; there is no way to avoid it.

Those that back this as a solution to transport only demonstrate a deep ignorance of basic physics, and fundamental engineering principles.

        drbuzz0 said:

It is not effecient at all.

In urban cycle, moving 1t car for transportation of 80kg of human is not efficient at all, sure.

And moving 300kg for transportation of 80KG of human is almost 3 times more efficient. This is the goal of compressed air car.

Lets just say that MTBF will be long, as all that fail often is removed…

Yes, sure, just try to tell me that you really think that the meaning of “robust” has to do with the number of refueling points…

The target of the first version is for internal use of some large companies, or for renting cars. The idea is to adapt the concept of free bicycle renting that is a huge success in Europe for public transportation. Refueling is part of float management.

Fair, this is all what i would need.

For the same price, you may only pay a third of the batteries for an electric car, with life end less than 4 years, so you don’t even get what you pay for…

You don’t even know what you talk about…

Composite materials are far more resistant that any metal equivalent nowadays. Ask to F1 pilots how their life cell is made.

So ask why many laptop companies had to recall all batteries… Exploding batteries when rated power or temperature are exceeded is quite difficult to handle…

Sure, and this is why firemen takes same tanks on their back with same pressure when they enter buildings in fire… Life of tanks is more than 12000 reloading cycles, only 32 years for one reloading per day, and 18 Millions of Km at 150km per reload.

Just try that with any batteries…

Yes, sure, i may just tell you that LEDs has been quite useful for cars now… And you don’t need any batteries to start the engine.

In fact, when anyone wants to be sure that a diesel generator will start, they use… compressed air.

You seems to know things better that aircraft companies. Like the meaning of “robust” word ?

Yes, sure, this is why a german company prefer to use compressed air than batteries to store production of their windmills…

Yes, sure, try to heat a ICE and wait to see it turning…

This is gaz pressure that push piston, all piston engine are compressed air engine.

But on ICE, you have to spend 1 rotation to prepare and burn the gazoline/oil/gaz, and another rotation to have the pressurized air push the piston, while using half pressure to pressurize the next cylinder…

In pure compressed air piston engine, without internal combustion, pressure is pushing every single rotation at full strength.

This is clearly better that any existing nuclear plant. But turbocharger are no more compatible with pollution standards.

Then these dreamed efficiency are posible on generators with stable speed, not with engine in urban cycle.

And engine efficiency is not at all car efficiency : if you need more than 1000kg to transport 80kg, you are close to 7,4% efficiency. Can you just tell me what is mean weight of running cars in the USA today ?

Why are you using your intelligence in such a perverse attitude ?

You say on one side about a 40% efficiency that

and for mechanical compression with efficiency more than 60%, this is “extremely ineffecient” ?

As i told you, it would be more efficient to use thermal compression like in the ICE… If this is excellent inside ICE, why would it be less than excellent at home ?